Ishbi-Erra in WilipediaIshbi-Erra was the first king in the Dynasty of Isin. When the Third Dynasty of Ur collapsed during the reign of Ibbi-Sin, and the former empire was overrun by invaders from Elam and elsewhere, Ishbi-Erra, who had until then served as governor of Isin, set-up an independent kingdom. This kingdom eventually reconquered much of the former heartland of Sumer and Akkad. Ishbi-Erra apparently never used the epithet 'king of Sumer and Akkad', which had been in use by all the Ur III kings, but the epithet was used by his grandson Iddin-Dagan[1].
According to the Sumerian King List, Ishbi-Erra ruled for 33 years (1953 BC - 1921 BC in the short chronology)[2], and was succeeded by his son Shu-Ilishu.http://en.wikipedia.org/wiki/Ishbi-Erra